Thomas wbightson



(No Model.)

UNITED STATES PATENT OFFICEo THOMAS WRIGHTSON, OF TEESDALE IRON WORKS,ENGLAND.

CENTER-CRANE.

SPECIFICATION forming part of Letters Patent No. 234,160, dated November9, 1880.

Application filed September 27, 1880.

To all whom it may concern:

Be it known that I, THOMAS WRIGH'rsoN, a subject of the Queen of GreatBritain, residing at the Teesdale Iron Works, near Stockton-on-Tees, inthe county of Durham, England, have invented certain new and usefulImprovements in Center-Cranes and in other mechanism in which in likemanner a jib or beam is supported by and movable with or about a centralstandard, (for which I have received Letters Patent in England, No.2,749, dated July 5, 1880,) of which the following is a specification.

This invention has for its object improvements in center-cranes and inother mechanism in Which in like manner a jib or beam is supported byand movable with or about a central standard.

In center-cranes as at present constructed it is usual to have ahorizontal `jib or beam carried upon the head of the ram of a hydraulicpress. The load, consisting, say, of the ladle containing the metal, isapplied at the outer end of the jib or beam, and by the injection ofwater to the cylinder of the press the ram, the jib or beam, and theload are all raised together vertically, and the load can be carriedaround a circular course either by the rotation of the ram Within thepress-cylinder or by the movement of the jib or beam upon the top of theram. At present the dimensions to which these cranes can be made arelimited by the very heavy strain which is experienced when a heavy loadis held suspended at the end of a long jib or arm.

According to my invention I relieve the central standard from thisstrain. For this purpose I arrange the jib or beam so that it may rockthrough a small angle. Near the two ends of the jib or beam I attach toit stay ropes or chains, which Ilead round over headpulleys suitablycarried above the standard, and I bring these ropes or chains togetherand connect them with a counterpoise. By this arrangement it resultsthat while the jib or beam is, as usual, under the control of thecentral press and can be raised and lowered by it, and while the jib orbeam is free to turn under the control of the center standard,nevertheless this standard is relieved (either in part or completely)from the tipping strain (No model.) Patented in England July 5, 1880.

by means of the stay ropes or chains, the overhead-pulleys, and thecounterpoise. The jib or beam by tipping tightens the stay ropes orchains attached to its more heavily loaded end, While the stays upon theother side become comparatively slack.

A very convenient arrangement for a cenF ter-crane is to have a centerpost supported at the bottom so that it may be able to turn freely. Thepost also has a top bearing. It may be in the roof of the building. rIhe lower part of the post is surrounded by a cylinder having glands atits ends, so that it can work up and down water-tight upon the post. Thepart of the post which works in the lower gland is larger than the partwhich works in the upper gland, so that when water under heavy pressureis admitted to the cylinder it rises up upon the post. The water isadmitted by a hydraulic pivot to the lower end of the post, and itissues by an aperture in the side ofthe post and is conveyed from it tothe cyl inder. At the top of the post there is a frame of pulleysreceiving the stay ropes or chains. The cylinder carries the jib orbeam, which, however, is not fixed to it, but is connected in such amanner that it is free to rock through a small angle. The counterpoiseis of an annular form and surrounds the post. I make the counterpoise ofabout one-half the weight of the load-it may be more or less-and I alsoput a weight-say one-half that of the load-at the opposite end of thejib or beam. In cases where it is inconvenient to employ a suspendedcounter-weight a small hydraulic press may be substituted.

In order that my invention may be fully understood, l have shown in thedrawings hereunto annexed a crane in which my improvements are embodied.

Figure l shows a side elevation, partly in section, of the crane. Fig. 2shows a horizontal section of the same, and Fig. 3 an end elevation,partly in section.

A is the central post, which, in order that it may revolve freely, Isupport in a water-pivot. Surrounding part of this post is a cylinder,B, which, by means of a key, is caused to turn with the post. C is asupport, attached, say,

to a roof, for supporting the top of the post. The cylinder is, asshown, provided at the bot- IOO tom with a gland of larger diameter thanat the top, so that by admitting water under pressure to the cylinderthe cylinder can be caused to rise upward on the post.

D is an arm orjib extending on two opposite sides of the post A.

E E are pivots at the bottom of thc cylinder, on which the arm or jib l)can have a slight rocking motion.

F is a frame tixed on the central post and carrying sheaves F.

G is an annular balance-weight surrounding the post, and connected bychains, which pass over the shea-ves, to the two arms ot' the jib D.

H is a ladle on one arm of the jib, and capable of containing, whenfull,eight tons of steel.

I isa balanceweight on the opposite arm of the jih, adjusted so as tobalance the cradle when the ladle contains half its charge, or tour tousot' steel.

Tile annular balance-weight G, l make pret'- erably of such weightaswill balance the whole four tous maximum prqionderating weight at anytime possible ou the cradle, or it might he of greater weight.

J showsthelowest position otbalauce-weight when cradle is raised.

K is the water-pivot supporting the bottom ot' the post A. The area ofthe ram of this pivot is arranged so that nearly the whole constantweight is balanced by the pressure ot' Water admitted into the cylinderot' the pivot to act upon the rain, the small remainder of the Weightcoming on a steel center.

L are radial pipes conveying water to and from machinery on the jib-arm;M, position 0f the same pipes when cradle is raised.

N is a cylinder for moving;` ladle to and fro along the arm; 0, positionol' valves for controlling the working of the crane, at which point isalso a platform, on which a man may stand to work the valves.

I is a water-passage from lower end ot' post A, by which water underpressure can pass to the radial pipes L L, and from them, hy a pipe, Q,to the valves at O.

R is a pipe for admitting water under pressure to and for exhaust fromthe lifting-cylinder.

S is a pipe for admitting water under pressure t0 and for exhaust fromthe back end of the cylinder by which the ladle is moved outing toradial exhaust-pipes V, which conduct the exhaust to an exhaust-passagein the post A, from which it passes out at the top through 6o arevolvingjoint at W.

The crane may be revolved by hydraulic or other machinery, or by hand,as desired.

I would state that, I do not conne myself to the means above describedfor controlling the movements of the cranes, as the valves for admittingwater under pressure to and for exhaust from the lifting-cylinder mightbe at any spot outside the crane andthe water-passage from the valves tothe lifting-cylinder be carried up through the center of the post orstandard. When this arrangement for working the lifting-valves isadopted the valves for controlling the movement of the ladle outward orinward along,r the arm may be controlled in any suitable manner.

l would state that, in place of water-power being used to raise andlowerthejib-arm on the post and to move the ladle inward or outwardalong the jib-arm, other mechanical means might be used to effect theseobjects.

Having thus described my invention and the manner of performing thesame, I would state that I claim- 1. The center-crane or other mechanismin which a jib or beam is supported by and movable with or about acentral standard., with the jib or beam projecting on two opposite sidesof the central standard and capable of rocking upon pivots at thestandard, and connected on both sides ot' the standard by chainspassinar over pulleys ou the standard to a balanceweight which can riseor fall, or to a hydraulic press or equivalent therefor, substantiallyas described.

2. The center crane constructed with the jib-arm projecting on twoopposite sides of the central standard and capable of rocking uponhorizontal pivots at the standard, and with a means of carrying the loadto he moved on one arm and a couuterbalanceweight of about one-half theload to be moved on the other arm, and with the two ends of the armconnected hy cords or chains passing over pulleys on the standard toacounterbalance-weight which can rise or fall, or equivalent therefor,substantially as described.

THOMAS WRIGHTSON.

Witnesses:

Geo. W. WILSON,

Stockton-on-Tees. ROBERT HowE,

So. Stockton.

